-- @owner: @kyeleze
-- @date: 2022/5/12
-- @testpoint: 自定义转换关系，显式转换;创建成功

--step1:建立自定义类型转换函数;expect:创建函数成功
create or replace function timezone_to_secondsinteger
(
    in time with time zone
)
returns integer
as
$$
declare
seconds integer;
begin
select (
extract(hour from $1)::integer * 3600
+ extract(minute from $1)::integer * 60
+ extract(seconds from $1)::integer* 1) into seconds;
return seconds;
end;
$$ language plpgsql;
/

--step2:创建显式转换关系;expect:创建转换关系成功
drop cast if exists (time with time zone as integer) cascade;
create cast(time with time zone as integer) with function timezone_to_secondsinteger(time with time zone);

--step3:调用创建成功的转换关系;expect:源类型转化为目标类型
select cast(time with time zone '02:02:02 pst' as integer);

--step4:清理环境;expect:清理成功
drop cast if exists (time with time zone as integer) cascade;
drop function if exists timezone_to_secondsinteger(time with time zone) cascade;
